Found some interesting reading with a lot of information about brining- "http://virtualweberbullet.com/brining.html". You may not agree with everything presented there, but I definitely learned more about brining meats.
From that site- "Discard the brine solution after use. The brine will contain proteins, blood, and other stuff from the meat that soaked in it. From a food safety standpoint, it is not advisable to reuse brine, even if it is boiled first."